Something New Has Arrived :~)

[One and a half]

@The Computer Audiophile, you may need some of that snow to cool the transformers, at low loads , reactive currents keep the temperature warm.

 

Good to see the ground can be tied together between the two , that’s really important for keeping the grounds the same potential.

 

There's enough difficulty in moving a 2 kVA around, let alone 5 .... your floor up to it?

[One and a half]

2 minutes ago, The Computer Audiophile said:

This floor is made of incredibly strong wood from the 1940s when houses around here were built very well. 

Ahh, in the days where QA didn’t exist and just by looking at the timbers, it would last a very long time.

Seems these days houses are made of pressed pine laminates and hardwoods a rarity; in our country anyway.

[One and a half]

27 minutes ago, fas42 said:

 My first good system 'worked' with no isolating devices in the mains line, but the electronics had good designs for their power supplies; meaty, and multiple transformers within. Would it have been more robust with better isolation? Indeed it would have, especially these days - the more you can fully shield the components from external interference, in every area, the better.

Same, for years went without an IT, and after installing one, realised what was wrong all those years listening.

[One and a half]

10 minutes ago, sandyk said:

 

 It appears to be way more of a problem in 60HZ 117VAC countries, or in high rise apartment buildings with lifts etc. elsewhere

Also if your house has many other contributors to generating rubbish.

 

Insidious, small scale, but numbers are a problem.

  Vampire SMPS like, microwave, phone chargers, routers, wifi extenders, TV & computers. 

Intermittent monsters

  Fluorescent lamps, oven, cooktop, washing machines, fridge, aircon, light switches

Worst offenders

Energy 'efficient' LED clusters, audio equipment - especially digital, just due to proximity

 

Audio Friendly house items

 Candles

 Soft furnishings

 Good earth (ground)

 Gas appliances

 

 

[One and a half]

45 minutes ago, sandyk said:

 Hi Gary

 In my experience, in most typical Au. suburban type areas, you only need a couple of decent mains filters at the right places to ensure no problems. ( I use 2 DIY filters including the attached with my P.C.)

 Failing fluorescent lights and cheap and nasty Energy 'efficient' LED clusters  can cause these problems, yet well designed equipment shouldn't normally be susceptible to the "Intermittent Monsters".

You do of course , however, need a decent Mains Earth .

 

Regards

Alex

 

Glad you brought that up.

Here is a typical circuit of an EMC filter.  Now draw a connection between the input neutral and earth (left GND).

 

For 120V and 230V TN networks where the neutral is bonded to earth at the panel (TN system) the potentials along the neutral to GND depend on the length of the wire run, but certainly is an impedance, small one, but it's there.

 

Observe cap CY2 on the output. Asymmetrical ICMN is very one sided in a TN system, the CY1 doing all the work, depending on impedances, let's say the voltage across CY2 is 2V-5V, if you're lucky ? The pair of caps are more or less the same as CX2, so another stage of differential rejection, fine, but common mode is more insidious. By design, the voltage across CY1 and CY2 should be 50/50. Well, why not give the two caps what they want, and tie the left GND to the 0V of a 120-0-120 or a 60-0-60 transformer. See what I'm getting at here. 

 

The main earth to the transformer is tied to this 0V, so the earth impedance to the source is very low 👍 as far as the filter is concerned. 

 

I can understand using the right GND terminal for the equipment earths, since the frame of the EMC filter is a shield in itself and opposes RF propagation. I use the 0V to terminate all earths from the equipment, since all earths are equal, but depends on the wiring and enclosures. The split reactors are a low pass filter at 50/60Hz, but not too sure where the line is drawn at the frequencies where the reactors attenuation falls off and the caps take over.

 

EMC filters are effective for digital devices where the AC current is small, but not that great benefit for power amps.

[One and a half]

38 minutes ago, fas42 said:

 

I devised my own design for a mains filter, which doesn't rely on items like current limited cores - this should be usable on the highest powered amps, because there was nothing to saturate, or limit peak currents. Note, it was not universal; the parts were such to match the, very typical, input side of the component's power supply.

 

Quite effective ... I injected massive 240V arcing noise into the mains, nearby - without filter, spluttering galore from the speakers; with, dead quiet system.

Oh, 'mine's bigger than yours', ok.🙄

[One and a half]

2 hours ago, cjf said:

I'm sure I am not understanding but how is this device a 5VA unit when the Input source assuming standard single phase power at 20A wall plug only generates 2400VA unless my math is wrong? It appears to also only have a 20A Input receptacle also. I didn't think transformers could create more power on the output than on the input unless they could somehow operate at above 100% efficiency ?

 

 

The transformer maybe wired for 240 V input and 120 V output. Upstream protection is sized accordingly, which is often tricky, since the fuse or breaker needs to allow the inrush to pass for the first 1/2 cycle (10ms for 50Hz systems, 8ms for 60Hz systems). Inrush current for toroid types can be 11-15 x rated continuous primary current. To make things easier circuit breakers are classified in IEC systems as Class A, B, C, D. Class A is for protection of non reactive elements such as heaters.

 

Class B for general outlets in the home or office. Class C and Class D for starting motors and transformers which allow time for the inrush, and will still protect against a short circuit, since that value is a lot higher and shorter duration. This is simialr to fast blo and slo blo in the fuse world. How slow is slo? There's curves for fuses which show the melting time of how much current and how long that current can be maintained.

 

A 5 A glass fuse can often be overloaded to 150%, but not for very long, follows an inverse time characteristic. A ceramic fuse of the same rating could handle more current due to the package's heat dissipation. 

[One and a half]

On 2/25/2020 at 2:35 AM, Lobbster said:

General question on Balanced Power Isolation Transformers implementation. Is it best to have them near the room outlet or is it equally effective wired in at the mains distribution panel using sheilded (BX) AC runs?

 

 TIA!

Dedicated line from the main panel to the audio system trumps a line conditioner plugged into a standard wired wall socket every day. Some iso transformers are noisy, when lightly loaded, and are best placed at the switchboard. Shielded cable from the Transformer is recommended, since the cable run can be some distance, and can pick up noise from other cables in close proximity. The worst kind of pickup is from a large circuit, like A/C or deteriorating light switches which don't switch clean, and create a click which is audible. Safe distance is 200mm (8 in).

[One and a half]

14 hours ago, tmfidelis said:

 

Installations have specific requirements unique to each room and playback or production system.

 

Recently, we worked with an electrician that provided a 120v 30A outlet, (NEMA 5-30). The outlet is approximately 30 ft. from the sub panel using 6-gauge wire with a twist at minimum of one turn every 1.0 ft.  The isolation transformer in this application is local with the electronics and provides power for everything in the system. (Each isolation transformer outlet is wired directly to the transformer.)

 

One should note that in room installations using existing electrical outlets may provide benchmark results providing there is ample current.

 

A practical application for dedicated lines from the main panel with an isolation transformer may be for cinema rooms that have a plethora of active and passive speakers.

 

Regards,

 

Tim Marutani

 

Agreed, in the context of 'power conditioner', the models typically have chokes (not the differential type), a set of caps, and a plethora of VDRs. The combo causes unpleasant reaction with linear audio equipment. As far as isolating the 'high' power and 'low' power device, how is it possible, other than to add in another choke. Power conditioners are great for printers and computers to provide for overvoltage protection, but not for audio use.

 

If your isolation transformer is quiet, then yes, it can be applied locally to the equipment. For those of with empty wallets, the Topaz type isolation transformers perform very well for their price, however they aren't spring chickens any more and tend to rattle at low power, and for that reason are best placed at the switchboard. The dedicated line adds more wire were noise is likely not to venture, and the HF currents end up at the transformer anyway, cancelled out when using a symmetrical supply (dependent on the transformer construction and symmetry of the windings).

 

[One and a half]

On 4/11/2020 at 11:42 PM, Foggie said:

@One and a half What if your service panel is located in listening room area with regard to something like a Topaz?  Can they be put outside?  Although we have some brutal winters

 

I have thought about adding a couple dedicated lines, but dread the thought of having rip all the sheet rock up etc..  From my understanding the power quality in my area is very good and conditioners et al would be a waste of $

Any electrical equipment outside is a challenge. The Topaz units are only indoor type. Even if it were placed outside in a weatherproof box, the design of the windings do allow moisture to creep inside and one day will pop. The box should have an anti-condensation heater, with an alarming system so that if the heater fails, it emits a warning....gets really messy. Any chance to install in a roof or under the floor?

 

Not all Topaz units are noisy, it's a lottery, I bought two, the 1kVA is noisier at low loads but not powerful enough to drive the whole system, the 2kVA is fine with no load.